This application claims priority of International Application No. PCT/DE99/01857, filed Jun. 23, 1999, which in turn claims priority to German patent Application No. 19831205.9, filed on Jul. 1, 1998.
The invention relates to continuously variable manual drives for seat adjusters and the use of such drives for longitudinal seat adjusters in motor vehicles.
A drive is known from EP 0 549 082 A1 which describes a continuously variable linear drive for a rail guide system for motor vehicle seats having two rails connected together and displaceable longitudinally relative to each other. The rails include, between them, a hollow cavity in which an adjusting element is mounted which is connected to one of the rails. The adjusting element engages teeth connected to or provided on the other rail and running in the longitudinal direction of the rail. With the known linear drive, the drive action is motorized for which a drive motor and a corresponding control and power supply are required.
Another drive is known from WO 98/25791 A1 in which seat adjustment is carried out by using a step switch mechanism which transfers a drive force to a gear element on the output side. A locking device is mounted in the power flow between the step switch mechanism and the output-side gear element to block torque transfer on the output side and enable torque transfer however on the drive side. In addition, in one embodiment there is a transmission between the drive and output sides of the step switch mechanism through which the drive force or adjusting path can be adjusted.
A manual drive operating on both sides, for seat adjusters in motor vehicles using a step-switch mechanism, is furthermore known from DE 195 27 912 A1 in which a drive lever is mounted on a drive axis and supports swivel locking elements whose free ends, which are provided with toothed elements, can be brought into engagement with teeth provided on the circumference of a drive wheel for the purpose of transferring force.
From DE 41 20 617 C2 a connection is known between a drive and an output having a locking coupling in which torque on the drive side is transferred in both directions of rotation to an output element while torque on the output side is blocked in both rotary directions by the locking coupling and is consequently not transferred to the drive element.
The known step switch mechanisms are used in particular in the motor vehicle field for devices for adjusting the height or incline of a seat. For this purpose they are set up to transfer a large force over a short path to an adjusting gear, such as is required in particular for moving a seat upwards on which the user of the vehicle seat is actually located.
The invention is concerned with the problem of providing a drive for longitudinal seat adjusters which enables a continuously variable adjustment of a vehicle seat, thereby always ensuring a crash-safe connection between the two rail devices of the vehicle seat and which is characterized by a simple cost-effective construction and a maximum individual flexibility for adjusting the seat on. In addition, a continuously variable manual drive for seat adjusters is to be provided which can be used universally and which enables a drive movement to be converted into an adjustment movement adapted to the events on the seat and in dependence on the requirements of any adjustment to be carried out.
These problems are solved according to the current invention. Advantageous and preferred developments of the inventions are given below.
A drive according to one embodiment of the invention is characterized in that the drive has a manual step switch mechanism which can be driven through a drive lever. In addition, a locking device is provided which blocks torque transfer on the output side but allows torque transfer on the drive side, and a transmission step is also provided which is coupled to the step switch mechanism on the drive side or on the output side.
With the drive according to the invention having a step switch mechanism for a longitudinal seat adjustment, the transmission ratio of the transmission step is selected so that the speed of the output element is faster than the speed of the drive shaft so that even with a drive lever, which can be operated on both sides as was hitherto used only for adjusting seat heights and inclines, an effective longitudinal adjustment of the seat can now be carried out.
Since the output-side gear element is always in engagement with the one rail device and is moved by manually operating the drive lever continuously in the one or other direction along the rail device, the solution produces a continuously variable drive which allows a precise adjustment of the longitudinal position of the seat even if it involves only small adjustment paths.
A further advantage of the drive according to the invention for the longitudinal seat adjustment lies in the fact that even during an adjustment process there is a high degree of security in the event of a crash since the gear element on the output side is always in engagement with the one rail mechanism and a displacement of the seat as a result of external forces is reliably prevented through the brake device. Using an active manually operable step switch mechanism instead of a motorized adjustment provides an additional simple and cost-effective solution.
Rail friction and rail pitch angles are insignificant in the case of an active longitudinal adjustment and do not prevent a precise length adjustment. This makes it possible, when necessary, to make the pitch angle of the rails so big that a separate seat adjustment can be eliminated. Thus longitudinal and height adjustment are coupled through the pitch angle of the seat rails.
The transmission step proposed according to the invention can be provided at several points of the drive. In a first preferred embodiment the transmission step is formed between a drive lever and the step switch mechanism. By way of example, force is transferred from the drive lever to the step switch mechanism through a toothed segment which is mounted on the rotary axis of the drive lever and engages in a positive locking element, more particularly a pinion, mounted on the drive axis of the step switch mechanism.
The drive axis of the step switch mechanism and the rotary axis of the drive lever thereby run parallel.
In another preferred embodiment, the transmission step is formed between the step switch mechanism and the locking device. For this embodiment, a transmission element is again preferred which is coupled both to the step switch mechanism and to the brake device and which engages, in particular, in a positive locking element mounted on the axis of the brake device. The transmission element is thereby preferably formed by the external teeth of a drive wheel normally provided in the case of a step switch mechanism.
In another embodiment the transmission step is formed between the locking device and the gear element on the output side. Force is transferred from the locking device to the gear element on the output side by means of a transmission element which is coupled on one side to the locking device and on the other to the gear element on the output side. The transmission element is preferably formed as a pinion which is mounted on the drive axis of the step switch mechanism and meshes with the gear element on the output side. The axes of the transmission element and the gear element on the output side thereby run parallel.
The locking device is any device which has the capacity to block forces which are introduced on the output side. A locking device of this kind is, in a preferred embodiment, a brake device as known from DE 41 20 617 AI.
However, the locking device according to the invention may also be a self-blocking gear which blocks forces introduced on the output side. A self-blocking gear of this kind is, for example, a tumbler gear which is known to one skilled in the art.
The step switch mechanism may be any drive device which produces a movement, more particularly a rotary movement, of an output element which is interrupted timewise (step-wise). As a rule, a drive force is likewise produced which is interrupted timewise.
A drive according to another embodiment of the invention for seat adjusters in motor vehicles is designed so that a step switch mechanism on the drive side and gear elements on the output side are connected together through a coupling device which in the non-actuated state maintains the power flow between the drive and the output-side gear elements by means of spring pre-loading and in the actuated state breaks the connection between the drive and the output-side gear elements. It is hereby reached that in the actuated state a passive seat adjustment is possible while in the non-actuated state an active adjustment is produced through the step switch mechanism.
The user now has the possibility of a rapid adjustment, for example, in order to move the seat quickly into the forward or backward position for climbing in or out of the vehicle, while a fine adjustment is undertaken by means of the step switch mechanism. There is thus a great deal of flexibility when making individual adjustments.
By uncoupling the output-side gear elements from the drive in the actuated state these can run freely along the one rail device, possibly in a longitudinal serration, without rotation or movement of the output-side gear elements becoming blocked by a brake device associated with the step switch mechanism.
In order to switch the coupling device in one preferred embodiment of the invention, there is an axially displaceable sleeve and an uncoupling operating element connected therewith, wherein the sleeve is moved axially against spring pre-loading during actuation of the uncoupling operating element to thereby break off the coupling between the drive and the gear elements on the output side. Through the axial displacement of the sleeve, positive locking elements of corresponding coupling regions are brought out of engagement, more particularly spring elements provided with positive locking elements are deflected so that the positive locking elements move out of engagement. By actuating the uncoupling operating element it readily becomes possible for the user to carry out a passive rapid adjustment.
Depending on the accessibility of the uncoupling operating element it may be necessary to assign the uncoupling operating element a switch element which when activated triggers the coupling and uncoupling process. This can be, for example, a press button which is preferably integrated into the drive lever so that an active adjustment and a passive rapid adjustment can be triggered or undertaken by the same operating element.
A continuously variable drive of the current invention is preferably designed so that the coupling device has positive locking elements or friction locking elements for carrying out the coupling process. The coupling device thereby has a first coupling region which is a constituent part of a gear element on the output side, and a second coupling region which is a constituent part of an element of the step switch mechanism or a brake device coupled to the step switch mechanism.
The coupling device preferably has an integral spring element acting radially or axially relative to the drive axis and provided with positive locking elements on the output side and on the drive side. During an uncoupling process a force is exerted opposite the pretensioning of the spring element in the axial or radial direction onto the spring element whereby the drive-side positive locking elements of the spring element move out of engagement with the corresponding positive locking elements of the brake device.
In a preferred embodiment of the invention, the spring element is formed in the manner of a plate spring whose spring region is divided up into several separately resilient segments with cogged free ends which can be coupled to associated positive locking elements of an output-side gear element or a part belonging to a step switch mechanism. A contour of the base surface of the spring element which is other than circular is assigned to a positive locking element of the corresponding other part and is connected in keyed engagement therewith.
The teeth of the adjoining segments of the plate spring are preferably off-set from each other by a fraction of a tooth spacing. This ensures that it needs, after an adjustment process, only a fraction of the tooth spacing until a new positive locking connection occurs between the corresponding positive locking elements of the plate spring and those of the step switch mechanism or brake device. After a rapid adjustment, a vehicle seat thus immediately returns back into its detent position. Thus, in order to ensure a reliable force transfer to the gear element on the output side, each two opposite segments of the plate spring have no stagger relative to each other so that in the non-actuated state always two segments of the plate spring are in engagement with the associated positive locking elements.
In a preferred embodiment of the drive, the step switch mechanism is formed as a drive acting on both sides for producing a rotary movement which takes place in one or other drive direction selectively starting from a neutral position of the drive lever, whereby the output-side gear element coupled to the second rail device is then only turned when the drive lever is moved away from the neutral position, whereas with a movement of the drive lever in the direction of the neutral position there is no rotation of the output-side gear element and thus no linear adjustment. Drives of this kind are characterized in that the user can directly carry out or influence an adjustment process by operating the drive lever in one or other swivel direction.
When using the drive according to the invention to make a longitudinal adjustment, the drive can produce a coupling in many ways between the output-side gear element and the one rail device.
Thus, the output-side gear element can be formed as a pinion or worm which engages in a longitudinally aligned toothed rod of the rail device. Alternatively, the output-side gear element is formed as a spindle nut or is connected to a spindle nut which engages in a longitudinally aligned spindle of the rail device. It is also within the scope of the invention to form the output-side gear element as a cable pulley which is connected to a cable, tensioned in the longitudinal direction of the second rail device and which can travel along the cable.